title: A peptide derived from the Wiskott-Aldrich syndrome (WAS) protein-interacting protein (WIP) restores WAS protein level and actin cytoskeleton reorganization in lymphocytes from patients with WAS mutations that disrupt WIP binding.
abstract: BACKGROUND
  The Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT) are caused by mutations in WAS, which encodes for WAS protein (WASP). The WASP-interacting protein (WIP) stabilizes WASP, as evidenced by severely decreased WASP levels in T cells from WIP-deficient mice. The majority of missense mutations in patients with WAS/XLT are located in the WIP-binding domain of WASP and might result in dissociation of the WASP-WIP complex and WASP degradation.
  
  
  OBJECTIVE
  To restore WASP levels and correct T-cell function in WAS/XLT patients with mutations in the WIP-binding domain of WASP.
  
  
  METHODS
  WIP, and a WIP-derived 41-amino acid-long peptide, which interacts with WASP and was designated nanoWIP (nWIP), were fused to enhanced green fluorescent protein and introduced by electroporation into EBV-transformed B cells, and by retroviral transduction into purified blood T cells from patients with WAS. WASP levels were measured by intracellular fluorescence-activated cell sorting staining. The actin cytoskeleton was visualized by intracellular phalloidin staining.
  
  
  RESULTS
  Introduction of WIP and nWIP restored WASP levels to normal in EBV-transformed B-cell lines from XLT patients with missense mutations in the WIP-binding domain of WASP and residual WASP levels, and corrected the defective spreading and pseudopodia formation of their T cells in response to immobilized anti-CD3.
  
  
  CONCLUSIONS
  A WASP-binding WIP-derived peptide stabilizes WASP in cells from XLT patients with missense mutations that disrupt WIP binding, and corrects their T-cell actin cytoskeleton defect. This may provide a novel therapeutic strategy for these patients.
authors.affiliation: Division of Immunology, Children's Hospital, Boston, MA 02115, USA. michel.massaad@childrens.harvard.edu
authors.forename: Michel J
authors.initials: MJ
authors.lastname: Massaad
authors.forename: Narayanaswamy
authors.initials: N
authors.lastname: Ramesh
authors.forename: Severine
authors.initials: S
authors.lastname: Le Bras
authors.forename: Silvia
authors.initials: S
authors.lastname: Giliani
authors.forename: Lucia D
authors.initials: LD
authors.lastname: Notarangelo
authors.forename: Waleed
authors.initials: W
authors.lastname: Al-Herz
authors.forename: Luigi D
authors.initials: LD
authors.lastname: Notarangelo
authors.forename: Raif S
authors.initials: RS
authors.lastname: Geha
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D015153:Blotting, Western; D002469:Cell Separation; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism* / Q000473:pathology; D018274:Electroporation; D005434:Flow Cytometry; D006801:Humans; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D019169:Jurkat Cells; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D020125:Mutation, Missense; D010455:Peptides; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000378:metabolism* / Q000473:pathology; D014161:Transduction, Genetic; D014923:Wiskott-Aldrich Syndrome / Q000235:genetics / Q000378:metabolism; D051316:Wiskott-Aldrich Syndrome Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D003598:Cytoskeletal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010455:Peptides; C109903:WIPF1 protein, human; D051316:Wiskott-Aldrich Syndrome Protein